M.G.
both my girls had problems with regular formula, my oldest was lactose intolerant and i tried the soy stuff but she wouldn't drink it, she would spit it back up immediatly after drinking it, then i tried the lactose free formula...back then they didn't have the A.R. or Gentlease stuff. my youngest has a milk allergy and i put her on nutramigen...the most expensive kind, but now i have the most happiest baby. no more diarrhea or gas or fussiness. they do say that soy products have more estrogen in them and that it can sometimes contribute to premature onsets of puberty...i remember reading that somewhere in some nursing journal. but then again, i'm sure there are lots of babies on soy and i haven't seen any of the boys running around with little boobies. (j/k)
if you are happy with the soy and he's happy, stay on it. don't switch up the formula to much cause then you'll get an unhappy baby. you are the mom, you know what's best. if you have any doubts, ask the doc. good luck. if you need anything else, just ask.